Peel the potatoes and cut them into thin round slices. Chop the garlic and rosemary finely and the onions into crescents.
Season the potato slices with the spices, add black pepper and salt.
Smear the bottom of a suitable tray with olive oil and pour in the white wine. Arrange the potato slices upright but don't press them too close together.
Pour olive oil over them and put them to bake in a preheated 356°F (180 °C) oven (with the fan on) for about 50 min. Serve the aromatic potatoes while still warm.